From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 26048 invoked by alias); 20 May 2009 15:37:38 -0000 Received: (qmail 26036 invoked by uid 22791); 20 May 2009 15:37:38 -0000 X-SWARE-Spam-Status: No, hits=-2.0 required=5.0 tests=AWL,BAYES_00 X-Spam-Check-By: sourceware.org Received: from hermes.mlbassoc.com (HELO mail.chez-thomas.org) (76.76.67.137) by sourceware.org (qpsmtpd/0.43rc1) with ESMTP; Wed, 20 May 2009 15:37:32 +0000 Received: by mail.chez-thomas.org (Postfix, from userid 999) id 118F53B5261B; Wed, 20 May 2009 09:37:31 -0600 (MDT) Received: from hermes.chez-thomas.org (hermes_local [192.168.1.101]) by mail.chez-thomas.org (Postfix) with ESMTP id B25203B5261B; Wed, 20 May 2009 09:37:30 -0600 (MDT) Message-ID: <4A1423BA.4000608@mlbassoc.com> Date: Wed, 20 May 2009 15:37:00 -0000 From: Gary Thomas User-Agent: Thunderbird 2.0.0.19 (X11/20090105) MIME-Version: 1.0 To: Ross Younger CC: Andrew Lunn , Simon Kallweit , "ecos-devel@ecos.sourceware.org" Subject: Re: NAND review References: <4A126D59.7070404@intefo.ch> <4A12B877.9030404@ecoscentric.com> <20090519141710.GJ20046@lunn.ch> <4A1410BA.3040808@ecoscentric.com> <4A1411F0.1070805@mlbassoc.com> <4A1420E3.20808@ecoscentric.com> In-Reply-To: <4A1420E3.20808@ecoscentric.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit X-IsSubscribed: yes Mailing-List: contact ecos-devel-help@ecos.sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Post: List-Help: , Sender: ecos-devel-owner@ecos.sourceware.org X-SW-Source: 2009-05/txt/msg00061.txt.bz2 Ross Younger wrote: > Gary Thomas wrote: >> I don't know what/where you were looking to come to these conclusions :-( >> Linux MTD has had the ability to use the RedBoot FIS directory for many (7+) years. > > At the moment, as I understand things, FIS implies io/flash, which pretty > much implies NOR. I don't have any plans to implement FIS on top of NAND; > people who do use NAND will generally be using a filesystem, so "obviously" > the right place to put static config data is on that filesystem? (Chicken, > meet egg?) I implemented FIS on NAND on the MOAB board in 2002 - it has been in the eCos tree since then. This also supported Linux 2.4 in the same time frame (the company that made the MOAB is out of that business, so that port has fallen by the wayside, but it has been done before, for a long time) And yes, that support was built on top of io/flash - not perfect and I'm not saying that the current discussion is out of line, but [IMO] proper partition support using RedBoot FIS on NAND is not a new idea. As for what to do if the block(s) containing the FIS directory are bad - this is a day-one problem for all such systems. That's why your EXTn file system writes out many "super blocks" so there is a fall back, etc. If there is a bad blocks replacement algorithm, use that (Linux MTD has pretty strong ideas about this for NAND which I suggest you follow), otherwise find another way to deal with such failures. > Now, if we were to need to write a primary bootloader - say, if a > OneNAND-based SOC came into the frame and we wanted to run RedBoot on it - > then we might very well find ourselves needing something along these lines. > A very very simple filesystem, combined perhaps with the ability to store a > little config data and/or partition table layout, for which it might be > worth considering reusing some or all of the FIS code? With that in mind, I > suppose that defining a scheme for a partition table and very simple FS for > NAND would be a worthwhile exercise, which could then of course be > contribbed to Linux. Comments? -- ------------------------------------------------------------ Gary Thomas | Consulting for the MLB Associates | Embedded world ------------------------------------------------------------